We approached the characterization of the mutations resulting in the inherited lysosomal disorders by addressing the genetic and molecular variants in the synthesis and intracellular routing of these enzymes. Using Gaucher's disease as a model, we demonstrated specific protein polymorphisms for each observed phenotype. We further demonstrated that phenotypic heterogeneity seen within these inherited disorders may be a consequence of different mutations, each affecting enzyme activity and influencing the processing, compartmentalization and/or stability of the lysosomal hydrolases. Although the understanding of the specific mechanisms responsible for clinical diversity has increased as a consequence of protein analyses, many of the primary pathophysiological processes have still not been well described. Recently we extended our understanding of these disorders by the application of recombinant DNA techniques to elucidate the structure of the gene(s) for these enzymes. The cDNA clones that we isolated have permitted the more complete description of the transcriptional and translation events. These cDNA clones have also permitted the localization of the gene for this enzyme by in situ hybridization, as well as the isolation of genomic clones. Restriction fragment length polymorphisms (RFLP's) have been identified. Northern and S1 nuclease analyses provide further details of the structure of the normal and mutant genes. The molecular mechanisms leading to nervous system involvement within these disorders have also been investigated. Western analysis and pulselabelling of normal and mutant glucocerebrosidase demonstrate that the several phenotypes of Gaucher's disease are caused by different mutations. We have also constructed human brain libraries from which cDNA for the lysosomal enzymes has been isolated. A comparison of these genes to those from non-neural tissues should provide further information on the regulation of tissue specific expression. The results of this research will provide a more rational foundation for therapeutic endeavors for these inherited disorders.